Check out solutions that use Gremlin here. Interested in something else? See the full list of technologies here.
For an enterprise level problem, you need an enterprise level solution. Datastax Enterprise (DSE) Graph allows you to traverse the data stored in your Cassandra DB, search it using Solr, visualize in DSE Studio and run analytics over Spark - all integrated within a single platform. View on Github
Graph databases leverage the connections that exist in your data to provide further insight into what your data actually means. JanusGraph in particular can be connected to a Cassandra DB backend and Elasticsearch for indexing, making it an obvious choice when dealing with distributed data pipelines. View on Github
Data visualization is particularly valuable when it comes to graph processing. If you are using graph technology due to the connectivity within your data, then you will want to visualize the connectivity and show it to your clients. Vega, being built on D3.js, comes with a powerful API to do just that. View on Github